by Tom Gaylord
Writing as B.B. Pelletier

Sheridan Supergrade right
My new Sheridan Supergrade is in fantastic condition, despite the wood check at the butt.

Sheridan Supergrade left
The cheekpiece makes the Supergrade stand out!

Part 1
Part 2

A history of airguns

This report covers:

  • Adjustable trigger!
  • Trigger-pull
  • Courage arrives!
  • Safety
  • Adjust the bolt handle position
  • Velocity
  • Test 1.
  • Test 2.
  • Test 3.
  • Pump effort
  • Summary

We’re back at it with the Sheridan Supergrade today. I will get to the velocity testing, but there are still a couple more surprises before that.

Adjustable trigger!

That’s right; the Sheridan Supergrade came with an adjustable trigger! Imagine that — an airgun from the 1940s with a trigger that adjusts.

The trigger adjusted in a unique way — by changing the location of the sear spring on a notched bar. To do this the rifle has to be out of the stock, which is not as straightforward as it is with some guns, so I won’t do it today. But I may work up the courage to try it at some point in our test.

Sheridan Supergrade trigger adjust
How about that? The instructions for adjusting the trigger pull.

Trigger-pull

Remember that I told you the action of this rifle feels like it hasn’t been used much? Well, the trigger is more of the same. It is two-stage and stage one takes 2 lbs. 13 oz. to complete. Stage two then breaks crisply at 6 lbs. 13 oz. That’s a bit heavy for me. I would like to see it break somewhere between 4 and 5 pounds.

Courage arrives!

After I had finished this report and set it up to publish I realized that the accuracy test came next. And I didn’t have Friday or Saturday to write it because the NRA Show was in town and I would be there all day, both days. And I don’t work on Sunday. So I had to shoot the rifle for accuracy and write that report this same day.

If I was going to do that I wanted the best trigger possible, so I suddenly found the courage to adjust the trigger. Following the instructions you just read I took off the stock and saw the trigger mechanism. It was nothing like what I imagined.

Sheridan Supergrade trigger
Move the leaf spring back in the direction of the arrow to lighten the trigger pull.

After I slid the spring all the way back the first stage pulled with 3 lbs. 1 oz. That’s right, it increased in effort. But stage two now breaks at 4 lbs. 10 oz, which is within the range I wanted. And it’s still crisp! How about that?

Safety

The safety is a rounded bar sticking up behind the receiver. It only works when the action is cocked. Pull back for safe and push forward for fire. This is the most unobtrusive safety Sheridan ever made!

Adjust the bolt handle position

Yes, there are even directions for adjusting the height of the bolt handle. However, since the breech seals by the bolt pushing forward, you must be careful to allow the bolt handle to be free of the stock with the bolt closed.

Sheridan Suppergrade bolt handle adjust
Adjusting the location of the bolt handle. Please overlook the incorrect capitalization and punctuation.

Velocity

Now let’s look at this Supergrade’s velocity. I will start with Sheridan Cylindrical pellets.

Sheridan Supergrade Cylindrical pellets
Vintage Sheridan Cylindrical pellets.

Test 1.

In this test we will see how the Supergrade performs with vintage Sheridan pellets on 3 through 8 pumps.

Pumps………Velocity……….Energy ft-lbs.
3……………….477……………7.58
4……………….539……………9.68
5……………….579……………11.17
6……………….610……………12.4
7……………….627……………13.1
8……………….653……………14.21

Test 2.

This is a retest of test 1 to check the numbers.

Pumps………Velocity……….Energy ft-lbs.
3……………….448……………6.69
5……………….576……………11.05
8……………….660……………14.51

Test 3.

Now we will look at two other pellets. First up is the 14.3-grain Crosman Premier that’s no longer made in .20 caliber.

Pumps………Velocity……….Energy ft-lbs.
3……………….424……………5.71
5……………….568……………10.25
8……………….670……………14.26

The velocity and power are low for a pellet that’s seven tenths of a grain lighter than the Sheridan pellet. I believe that is because the Crosman pellet is made from lead that’s hardened with antimony, and it doesn’t agree with the Supergrade’s phosphor bronze barrel.

Next we will look at the JSB Exact dome.

Pumps………Velocity……….Energy ft-lbs.
3……………….488……………7.26
5……………….598……………10.91
8……………….686……………14.35

Even though this pellet is lighter than the Premier, it still produced greater energy. In a pneumatic the heavier pellet should usually produce the greatest power. But the JSB is made from pure lead, where the Premier is made from hardened lead.

Pump effort

Now, let’s see how hard it is to pump the Supergrade.

Pumps……Effort
1……………15
2……………24
3……………29
4……………33
5……………35
6……………36
7……………36
8……………37

Summary

That’s a pretty good look at the rifle’s performance. As you can clearly see, the application of automatic transmission sealant did increase the rifle’s velocity by 25-30 f.p.s. And the increase seems to be holding.

I have seen so many revelations in this test! The manual is a treasure trove of information about an air rifle that was designed even better than I had imagined, all these years.